Apparatus for recording light



May 15, 1923. 1,455,074

. T. W. CASE APPARATUS FOR RECORDING LIGHT Filed Dec. 11. 1920 4 Sheets-Sheet 1 2 f m/vron May 15, 1923.

T. W. CASE APPARATUS FOR RECORDING LIGHT Filed Dec. 11, 1920 4 Sheets-Sheet 2 May 15, 1923. 1,455,074

T. W. CASE APPARATUS FOR RECORDING LIGHT Filed Doc. 11, 1920 4 Sh'ets-Sheet s May 15, 1923.. 1,455,074

T. W. CASE APPARATUS FOR RECORDING LIGHT Filed Dec" 11 1920 4 Sheets-Sheet 4 Canon 5 a Faar Ganil ZIf/YVE/VTOR ,Br

- of makin record sheet for use I Patented May 15, 1923.

THEODORE WILLARD CASE, OF SCIPIO, NEW YORK.

APPARATUS FOR RECORDING LIGHT. I

Application fi1ed.IDecember 11, 1920. Serial No. 480,095.

To all whom it may con 0cm Be it known that I, THEODORE W. CASE, of Scipio, in the county of Cayu a, in the State of New York, have invente new and useful Improvements in Apparatusfor Recording Light, of which the following, taken in connection with the accompanying drawings, is a full, clear, and exact description.

This invention relates to certain improve ments in apparatus for recording light.

The main object of the invention is the production of an apparatus that is capable a record of light, readable in known'umts, such as foot candles.

Another object is the production of a in connection with such an apparatus.

.Another object is the utilization of variations in light to automatically control, through relays" -or other means, sources of artificial light, or means for excluding or admitting natural light, or for actuating a signal, etc.

a further use of Other objects and advantages relate to the details of construction and operation of the apparatus, all as will more fully appear from the following description, taken in connection with the drawings, in which:

Fig. 1 is a diagrammatic view of the electrical connections of'an. apparatus of my invention. m

Fig. 2 is a diagrammatic view of the circuits of a constant speed motor for driving the mechanical parts of the apparatus.

Fig. 3 is an elevation of the recording mechanism.

Fig. 4 is a view of a portion of the apparatus of Fig. 3 in an unbalanced condition.

Fig. 5 is a sectional view of the pen and its parts.

Fig. 6 is an elevation of the sheet feeding mechanism.

Fig. 7 is a top plan view of the wheel that carries the slide wire.

Fig. 8 is a rear elevation of a portion of the recording mechanism illustrating the actuating means for the pen.

Fig 9 is a view of a record sheet of my invention.

Fig. 10 is a diagrammatic illustration of the invention.

Generally speaking, the broad thought of the invention is the utilization of a light re-active device, such as a photo-electric cell, or perhaps some other light re-active resistance for varying an electric current, such variations being in any suitable way translated into a record, which will correspond to the variations in the light reactive device, and may, therefore, be calibrated to indicate in known units the intensity rays to which the light reactive device 18 ex'posed.

When a pen or other record making instru nent is used, its movement, or the movement of any other part of the recording mechanism may be utilized as a relay to transmit similar movement to other mechanism, or to .actuate a device or devices controlling light producing or governing apparatus, to maintain, if desired, substantial uniformity of light intensity, or to actuate means controlling artificial light.

The record mechanism is generally the same as that used in the Leeds & Northrup temperature recorder, as for instance illustrated in Leeds Patent No. 1,125,699 dated January 19, 1915, and is fundamentally a. self-balancing potentiometer. tiometer provides:

of the The potenable electromotive force; and

Second: Suitable electrical connections for bringingthat electromotive force 'to a point where it may be balanced against the unknown electromotive force which results from variations in the resistance of the photo-elcctriccell dependent upon the 1ntensity of the light rays to which the cell is exposed. v

The two circuits are connected with opposite polarity, or so that the two E. M. Fs oppose one another. Measurements are made'with the potentiometer by varying a known electromotive force until it equals the unknown. When the two are equal, the index of the potentiometer-the galvanometer needle-stands motionless, and this needle is the controlling means of the recording apparatus.

Only a general description need be given slide wire type. The battery 1, which may consist of a few dry cells, supplies continuously flowing current to the potentiometer circuit, the current being maintained constant by rheostat 2-. As the voltage in the battery 1 changes, the current in the potentiometer circuit will also change. To compensate for this change, a portion of the battery voltage is compared at intervals with the constant voltage of the standard cell -8, and the rheostat -2 is adjusted until the proper current is flowing. This is accomplished by completing the circuit at +l, which connects the galvanom eter -5 in series with the standard cell across the resistance coil -6. If the voltage across the coil is not equal to the voltage of the standard cell, the galvanometer will deflect from its zero position, in which case the rheostat 2 should be adjusted until the galvanometer returns to its zero position. The two voltages are now equal and opposite, and the proper current is flowmg.

A battery --7 of suitable electromotive force is connected in circuit across the electrodes 8 and 9 of the photo-electric cell. A variable resistance -10 is inserted in the circuit bet-ween the electrodes of the photo-electric cell so that there is a drop in potential between the points -11- and -12, causing a flow of current through the circuit thus formed.

In addition, the current flows through the photo-electric cell to the contact 13, which contact is movable with respect to the slide wire 14:, the current returning through the galvanometer and wire 6 to the battery 7. Variations in the current flowing in this circuit effected by variations of resistance in the photo-electric cell will cause deflection of the galvanometer needle, but the needle will again return to its zero position when a proper adjustment of the slide wire with respect to contact 13- is made, so that the currents flowing in two circuits balance each other.

The resistance 10 should be made adjustable so that if any variationswin the sensitivity of the photo-electric cell occur by reason of use or variations in manufacture, the resistance may be used to account for such variations.

The movement of the galvanometer effected by variations in current-in the photoelectric cell circuit is utilized to control the recording mechanism. All of the actual work of operating the recording mechanism is performed by the constant speed motor 15- but the extent of the work and its direction are controlled by the galvanometer.

shown, and which controls the Contact 17- forming a portion of the electric circuit of the motor. When the motor slows down, the circuit through contact 17 is closed, but such action as seen in Fig.2 short circuits the resistance, thereby allowing greater current to flow in the motor circuit causing the motor to speed up when the reverse will take place.

The electric motor drives shaft --18, which shaft carries a pair of cams 19 and 20-, the one 19 for periodically moving the clutch lever -2-1- carrying one member 22 of a clutch, the other member of which is the disk 23 mounted upon the shaft 24. The other cam -20- periodically raises the rocker arm 25 to such an extent that the arm serves to periodically raise the needle, or pointer 26- of the galvanometer. It will be noted that when the rocker arm -'25 raises the galvanometer needle, the clutch member 22- is out of contact with its co-operating disk. When the circuits of the potentiometer are balanced, the galvanometer needle is positioned, as shown in Figure 3, that is, directly beneath the space between the angle levers 27 and 28,

pivoted respectively at -29 and 30.

Under those conditions, upward movement of the rocker arm effects no movement of the angle levers. Should, however, the galvanometer needle be deflected so" as to lie beneath either one or the other of the angle levers at the time of upward movement of the rocker arm, then the angle lever under which the galvanometer needle lies will be moved about its pivot, and in turn will actuate the clutch member 22' and turn such member about its pivot.

The slide wire l4- is mounted on the same shaft as the disk -23 and may, as shown, be mounted upon the circumference. of a second disk, or wheel 31-. For the purpose of returning the clutch member 22- to its normal position, thereby effecting rotation of the co-acting clutch member 23, the shaft -18 carries a pair of cams 32- and '33--, contacting respectively with the opposite ends of the clutch member -2l, which member, after movement of the rocker arm 25, is again brought into contact with its co-aoting disk 23 and is moved from position shown in Figure 4 ,to that shown in Figure 3- by means of the cams 32 and 33 to the position shown in Fig. 3, thereby effecting rotation of the disk 23-- a distance dependent upon the extent to which the clutch member 22- was originally unbalanced by movement of one ofthe lever arms 27- or -Q8, and the extent of movement of the said lever arm is dependent entirely upon the amount of deflection of the galvanometer.

Th r fore, h ext t of mov ment of disk -23- corresponds with the extent of deflection of the galvanometer needle, and as the slide wire 14: is mounted on the same tric cell is subjected.

The recording instrument, as the pen -34 is slidably mounted upon a stationary shaft so as to move laterally across the record sheet, which may be mounted in any suitable way, as upon roller 36-. The pen-carrying parts -37- are directly connected to a suitable member as violin string 38-, which transfers: to the pen lateral movement in direct accordance with the movement of the-disk -23 and therefore, the galvanometer needle. I F

As shown, the violin string may be wound about the shaft 24' or aroundr any suitable disk or member rotating with said shaft so as to convey -a movement of the pin in direct accordance with the movement of said shaft, as effected indirectly through the movement of the galvanometer needle.

As the pen moves across. the record sheet,

as shown in Figure 9, and which may be mounted upon the roll, or platen, 36 for positive rotation therewith, it will trace upon said sheet a line which will be indirect accordance with the variations in light to which the photo-electric cell is exposed. The

record sheet may be arranged to move at any desired pre-determined speed, as for instance three (3) inches to the hour, and may be vcalibrated along one of its longitudinal edges in time units, as illustrated, while 1 along its end portion it may be calibrated in light quantities as foot candles, and the sheet illustrated is adapted to be so cali- 'fi brated from zero to 10,000 foot candles, as

, shown.

artificial light, etc.

From the above, it will be readily understood that the apparatus described will produce a record of the intensity'of the rays of light to which the photo-electric cell has been exposed during the period of time shown upon the record, which record-may be calibrated in units of time and light intensity. In Figure 10 I have diagrammed a means for utilizing the recording mechanism to actuate asignal relay or other device, as a switch to actuate and control a source of For this purpose, the movable carria e for the pen is provided with a contact member -39- which may be in the form of a spring, and adapted to close an electric circuit through the adjustable contact 40 and battery -41 when the pen is moved by the recording mechanism to a pre-determined position along the shaft 35. The circuit so formed may include a signaling device as 42 or a relay as 43-, or both.

For instance, the contact -40 insulated give notice when a predetermined light intensity is reached. E

It will be understood that the circuit closed by movement of some part of the recording apparatus, as the pen or its carriage, may

be utilized as a relay for any purpose, or merely for producing a signaL and for the purpose of the claims herein,the words Indicating device are deemed to include a signal such as a bell, a relay, a switch, or equivalent devices.

Although l have shown and described a specific apparatus capable of accomplishing the objects of my invention, I do not desire to limit myself to the particular apparatus or its details of construction or operation, as many and various changes maybe made -in the apparatusand the details of its construction and operation, without departing from the invention as set forth in the appended claims.

What I claim is:

1. In an apparatus of the class described, an electrical circuit containing a (known but variable electromotive force, a second circuit coupled with the first circuit so that the electromotive forces of the two circuits oppose each other, alight reactive resistance an a potential in said second circuit and means for varying the electromotive force of the first circuit so as to equal the electromotive force of the second circuit as the latter is varied in accordance with variations the electromotive forces of the two circuits latter is varied in accordance with variations in the resistance of said'light reactive resistance, and means for making aline record of said variations.

3. A light recording apparatus comprising the combination with a record sheet, of a galvanometer, a circuit including the galvanometer, and a light reactive resistance, means rotated a distance and in a direction dependent upon the extent and direction of deflection of the galvanometer, and means actuated by said rotated means for making a record upon said sheet of the intensity of the light to which said light cell is exposed while the latter is in stationary position.

4. -A light recording apparatus comprising a galvanometer, a circuit including the galvanometer and a light sensitive cell,

means rotating a distance and in a direction dependent upon the extent and direction of deflection of the galvanometer, and means actuated by said rotated means for making. a record of the intensity of the light to which said light cell is exposed.

5. A light recording apparatus comprising an electrical circuit including a light sensitive cell, means in said circuit affected by the change in current flowing therein as varied by the intensity of the light to which said cell is exposed, a member rotated a distance and in a direction dependent upon said affected means, and a recording device actuated by the rotated member.

6. A light recording apparatus comprising an electrical circuit including a light sensitive cell and a galvanometer, mechanism actuated in accordance with the deflection of said galvanometer for producing a record of the intensity of the light to which said cell is exposed.

7. A light recording apparatus compris ing an electrical circuit including a galvanometer and a light sensitive cell adapted to be maintained in stationary position, mechanism a ctuated in accordance with the deflection of said galvanometer for producing a record of the intensity of the light to which said cell is expose when in stationary position.

. 8. A light recording apparatus comprising the combination with a record sheet calibrated in units of light intensity and time periods, of a galvanometer, a circuit including the galvanometer and a light sensitive cell, means rotated a distance and in a direction dependent upon the extent and direction of the deflection of the galvanometer and means actuated by said rotated means for making a record upon said sheet of the intensity of the light to which said light cell is exposed.

9. A light recording apparatus comprising the combination with a record sheet calibrated in units of light intensity and units of time, of an electrical circuit including a light sensitive cell, means in said circuit affected by the changes in the current flowing therein as varied by the intensity of the light to which said cell is exposed, a member rotated a distance and in a direction dependent upon said aflected means, and a recording device actuated by the rotating member for producing a record upon said sheet of the intensity of the light to which said light cell is exposed.

10. A light recording apparatus comprising the combination with a record sheet calibrated in units of light intensity and units of time. of an electrical circuit, including a light sensitive cell and a galvanometer, mechanism actuated in accordance with deflections of said galvanometer for producing a record upon said sheet of theintensity of the light to which said cell is exposed.

In witness whereof I have hereunto set my hand this 27th dav of November. 1920.

THEODORE WILLARD CASE. Witnesses:

EARL I. SPONABLE,

Buss S. CUSHMAN. 

